Air mileage register for aircraft



Jan. 19, 1943.

T. W. ROYER AIR MILEAGE REGISTER FOR AIRCRAFT Filed May 2, 1940 1 'lllllf'lllll.

INVENTOR.

Patented Jan. 19, 1943 UNITED STATES PATENT OFFICE AIR MILEAGE REGISTER FOR. AIRCRAFT Thurber W. Royer, Dallas, Tex.

Application May 2, 1940, Serial No. 332,899

2 Claims.

This invention relates to aeronautical instruments and it has particular reference to an air mileage odometer for airplanes.

Another object of the invention is to provide means of integrating time with speed to obtain an indication of air miles traversed by an airplane.

Another object of the invention resides in the provision of means by which air miles traversed are measured in direct relation to speed and time.

Other objects and advantages of the invention will become manifest as the description proceeds, taken in connection with the accompanying drawing, wherein:

Figure 1 is a schematic view of the invention.

Figure 2 is a plan view of the time controlled disc and its electrical relationship with the mileage indicating mechanism.

Figure 3 is a fragmentary detail view, partly in section, showing the construction of the disc.

Continuing with a more detailed description of the drawing, reference is primarily made to Figure 1 in which is shown the speed indicatin mechanism which constitutes in part the ele ments of the present invention. This mechanism i comprised of the conventional air speed indicator Pitot tube I, which is directed into the air stream of the airplane and communicates with the bellows 2. As the velocity of air flow past the Pitot tube increases with increased speed of the airplane, the bellows 2 expands and in so doing, moves the arm 3 against the pointer I, the latter being pivoted at 5. The pointer moves over a calibrated segment 6, on which is borne numerals indicative of miles per hour. While any suitable connection between the arm 3 and pointer 4 may be employed, a pin I is shown affixed to the arm, which enters an elongated slot 8 in the pointer in order to accommodate the differential movement. A spring 9 counteracts the urge of the bellows 2 and returns the pointer 4 to its original position when moved as described. An adjustment Ill is afforded through the medium of which the tension of the spring may be varied for minute adjustment.

Associated with the elements just described is a bellows II, somewhat smaller than the bellows 2 and which is provided with an arm I2, pivoted at I3 to the pointer arm 4. The purpose of this bellows is to provide means to compensate for responding to sea level pressure, when the bellows are slightly past their fully extended position as installed in the instrument. As higher altitudes and consequently rarifled atmosphere are reached, the bellows attempts to expand in ratio to the diminishing atmospheric pressure, hence exerting a correspondingly greater force on the pointer arm 4, moving the latter to higher graduations on the scale 6. Thus, as the density-altitude of the ship is increased, the decrease of atmospheric pressure would cause the speedometer needle to be moved proportionally to indicate the higher speed. Q

To compute the number of air miles traversed, a disc I4, shown fragmentarily in Figure 2, is provided, having a multiplicity of contacts I5, insulated one from another by means of a mat of non-conductive material I6. These contacts I6 are equi-distantly spaced about the edge of the disc while a second series of identical contacts I! are spirally arranged on the disc from the perimeter inwardly toward the center thereof, as shown in Figure 2. The purpose of these contacts will be presently described.

The disc I4 is rotated at a predetermined rate of speed by means of a clock mechanism I8. Speed of rotation is in relation to the number of contacts carried by the disc I4 but it is preferred that the disc be revolved at the rate of 1 R. P. H. for reasons to become apparent presently.

Connected to and moved longitudinally by the bellows arm 3 is a brush I9. This brush is so arranged that it will be constrained to move toward -the-center of the disc I4 as the speed of the ship is increased and being so acutated, it is contacted successively by the points I5 along the edge of the disc. The variables of the system, such as the tension on spring 9, are so arranged that the points I5 are first contacted by the brush I9 when the air speed of the plane reaches the minimum cruising speed, say, sixty M. P. H.

In order to provide current to the disc contacts I5 and IT, a collar A surrounds the shaft B of the disc and carries a con-tact brush by which current is supplied from batteryC through solenoid S of the odometer and through wire D. The circuit is completed through the brush I9 moving over the contact points I5 and H. A switch E is arranged in the circuit, as shown.

At this speed, sixty contacts are made by the brush IS with the points I5 each time the disc is rota-ted, which occurs once each hour, as explained. When each impulse is thereby made, the odometer 20 registers one mile and in the course of one revolution, which occurs in .one

- traversed during the hour.

hour, the odometer will have registered 60 times, indicating 60 miles, which is the distance that the plane has traveledin one hour at a speed of 60 M. P. H.

Assume the speed to be increased for the next hour to 61 M. P. H. 61 contacts will have been made during the course of the hour since the 60 contacts I5 have contacted brush is as well as the outermost of the series of spirally arranged contacts IT. The odometer will have registered 61 times representing 61 miles, the air miles As the speed of the airplane is further increased, the brush I9 is still further advanced toward the center of the disc ll, thereby picking up additional contacts which will cause the odometer to register the increased number of miles traversed in a given period of time.

Obviously, such variables as the minimum cruising speed of the plane, the speed of rotation of the disc [4, the number of contacts on the disc, the spacings on the scale 6, and the strength of the spring 9, etc., may be varied over a wide range, provided that the average M. P. I-L, multiplied by the time in hours, is accurately computed by the odometer 20.

Manifestly, the construction as shown and described is capable of some modification and such modification as may be construed within the scope and meaning of the appended claims is also 1. An air mileage indicator for aircraft including an expansible air pressure responsive means, an electric circuit, a clock actuated disc disposed in said circuit carrying a multiplicity of closely associated and spirally arranged electrical contacts, an electro-magnetic counter also in said circuit, and means actuated by the expanding and contracting movements of said air pressure responsive means and engageable with the contacts oi said clock actuated disc to open and close said circuit in accordance with the varying speeds 01 said aircraft, to actuate said counter.

2. An air mileage indicator for aircrait including an expansible air pressure responsive means, an electrical circuit, an electro-magnetic counter arranged in and actuated by said circuit, a disc arranged to rotate at a predetermined rate of speed, a spirally arranged series of closely associated electrical contacts in said circuit, on said disc and separately insulated, and means actuated by said pressure responsive means and cooperating with said electrical contacts for translating electrical impulses eflected by said contacts on said circuit into miles to be computed by said magnetic counter.

THURBER W. ROYER. 

